The present invention relates in general to inserts for tools used in machines for breaking up surfaces such as concrete and asphalt roads, and in tools used in mining, such as for coal, trona, potash and salt, and it relates in particular to improved inserts for use in such tools.
One type of machine which is used to break up concrete and asphalt pavements and other hard surfaces utilizes a plurality of tools mounted on a cutting wheel which is forced against the surface to be broken. Each tool has an elongate steel body at the forward end of which is a tungsten carbide cutting tip. When the cutting wheel rotates, the tools are carried through a circular orbit and the tungsten carbide cutting tip penetrates the surface to be cut. When the wheel is forced against a surface, the carbide tip of each tool removes a small amount of material, thereby advancing the cut into the surface.
The bodies of the cutting tools are formed of steel and are rotatably retained on the wheel such that each cutting tool is rotatable around its longitudinal axis so as to symmetrically wear the tool, thereby extending the life of the tool and the carbide cutting tip attached thereto.
Typically, each of the steel tools has a socket at the forward end thereof into which is brazed a base on the rearward end of the tungsten carbide insert. Each of the inserts has a base portion suitable for attachment to the socket of a tool, and forwardly of the base a tapered central body with a conical or semi-spherical forward cutting end. Such inserts have an overall length of about 1/2 inch to 1 1/2 inch and a maximum diameter from about 5/8 inch to 2 inches. Because of the large number of inserts which are used in a typical cutting or excavating machine, it is very important that each of the inserts has a long useful life and resists wear, cracking and remain securing attached within the socket of the tool.
My prior application, Ser. No. 114,832, describes an improved insert having a forwardly disposed cutting end, an elongate central body and a base, and a plurality of buttresses extending from the base to the central body. The application further describes the benefits of an insert having an axial core of a harder grade of tungsten carbide than the outer portions of the cutting tip.